This observational study is being done to learn more about heart attack recovery in patients supported with the Impella 5.5 left ventricular assist device (LVAD) as part of their standard of care. There are three stages in this study: screening, treatment and post treatment. There will be two phases of enrollment: First phase will enroll 10 patients; second phase will enroll an additional 40 patients. Approximately 50 participants will take part in the study at Columbia University Irving Medical Center. Participation in this research is expected to last approximately 14 months. This time estimate includes a screening period for about 1- 3 days, treatment period of 40 days and post treatment follow-up period for 1 year. Data will be collected through 1- year after heart transplant. Clinical data (medical history, vital signs, laboratory assessments) from medical records, to perform functional testing, and to obtain blood and discarded heart tissue fromfor the purpose of this research study. Participants will be asked to share their records for echocardiography, right heart catheterization, laboratory data and clinical information. Participants are required to complete an assessment a 6-minute walk, and hand grip strength test.